if the amount of radioactive iodine-123 in a sample decreases from .400g to .100g in 26.2 hours, what is the half-life of iodine-123

Answer 1

ln(No/N)=kt
Substitute No = 0.400
N = 0.1
k = unknown.
t = 26.2 hrs.
Then k = 0.693/t_1/2
You know k, solve for t_1/2